1. Field of the Invention
The present invention relates to a draw out type air circuit breaker, and in particular to a draw out type air circuit breaker which is capable of distinguishing accurately a disconnected position, a testing position and a connected position when a breaker is pushed in/drew out from a cradle.
2. Description of the Prior Art
Generally, an air circuit breaker is installed between a load equipment and electric power in order to protect the load equipment such as a motor and a converter, etc. and a line from an abnormal current (a short circuit, a ground fault, an over current) generated at an electric circuit such as a power transmission/distribution line and private power transforming facilities, etc. Particularly, an air circuit breaker is a breaker for extinguishing an arc generated in opening and closing of a contact within the air.
An air circuit breaker is divided into a fixed type fixedly installed between an electrical power and an electrical load and a draw out type in which a breaker is movable so as to be separated from a power terminal and a load terminal in order to facilitate maintenance and secure stability.
FIG. 1 is a side view illustrating a state in which a cradle is separated from a breaker body in a general draw out type air circuit breaker being applicable a position indicating apparatus in accordance with the present invention.
The draw out type air circuit breaker includes a cradle 100 having an opened side toward a breaker body 200 and provided with a power source terminal 202 connected to electrical power source and a load terminal 204 connected to an electrical load equipment, a breaker body 200 movable so as to be pushed in/drew out from the cradle 100 and connecting or disconnecting a circuit between the power source and the load, and an interlock apparatus 300 for indicating a present position such as a disconnected position, a testing position, a connected position of the breaker body 200 when the breaker body 200 is pushed in/drew out from the cradle 100.
Herein, connectors 206, 208 are respectively connected to the power source terminal 202 and the load terminal 204 of the cradle 100, the connectors 206, 208 are respectively connected to a power source terminal 210 and a load terminal 212 projected from the breaker body 200, accordingly the cradle 100 and the breaker body 200 are mechanically and electrically connected each other.
And, the cradle 100 includes a guide frame 214 for guiding the translocation of the breaker body 200 when the breaker body 200 is pushed in/drew out.
FIG. 2 is a side view illustrating an interlock apparatus of a draw out type air circuit breaker in accordance with the prior art.
The interlock apparatus in accordance with the prior art includes a base frame 102 fixed to the breaker body 200, a lead screw 104 supported by the base frame 102 so as to be rotatable, a screw pipe 106 fixed to the cradle 100 and inserted by the lead screw 104, a position indicating apparatus 108 installed on the base frame 102 and for indicating a position of the breaker body 200 when the lead screw 104 is meshed with the screw pipe 106, and a lock slide 110 connected to the position indicating apparatus and for locking a position when the breaker body 200 is placed at one of the disconnected position, the testing position or the connected position.
The position indicating apparatus 108 includes a lead bar 112 placed so as to be parallel with the lead screw 104, abutted to one wall surface of the cradle 100 and retreated relatively when the lead screw 104 is meshed with the screw pipe 106 and linearly moves, a cam 114 connected to the lead bar 112 and installed on the base frame 102 so as to be rotatable in order to perform a rotation motion while retreating of the lead bar 112, and a indicating means 107 connected to one end of the cam 114 and for indicating a position of the breaker body 200 by linearly moving in accordance with the rotation of the cam 114.
In the lead bar 112, a lead bar 112 is a rod shaped member having a predetermined length and portion of the lead bar 112 is installed at the side of the lead screw 104 so as to be parallel with the lead screw 104, the other portion of is the lead bar 112 is curved so as to be inserted into a slot 118 formed at the cam 114.
And, a breakaway preventing member 120 for preventing a breakaway of the lead bar 112 from the slot 118 is installed on the end of the lead bar 112 inserted into the slot 118.
A return spring 122 for providing an elastic force in order to return the lead bar 112 to an its original position after operation is installed between the breakaway preventing member 120 and the base frame 102.
The cam 114 has a hinge portion 126 so as to be rotatively installed to the base frame 102, a slot 118 in which the lead bar 12 is inserted is provided at the lower portion of the hinge portion 126 so as to be curved a certain times at a predetermined angle, and a connection pin 124 connected to an indicating plate 150 placed at the front of the hinge portion 126.
As depicted in FIG. 3, the indicating means 107 includes an indicating plate 150 placed at the rear of the base frame 102 so as to be linearly movable up and down, a front plate 152 placed at the front of the indicating plate 150, and a guide plate 154 placed a the rear of the indicating plate 150, fixed to the base frame 102 and for guiding the up and down movement of the indicating plate 150.
The indicating plate 150 is a flat plate and is provided with a color indicating portion 156 on the its upper front surface in order to indicate a position of the breaker body 200 with colors, and a connection pin 124 of the cam 114 is connected to one side surface of the indicating plate 150.
The front plate 152 is placed at the front of the indicating plate 150, fixed to the base frame 102 and has three display windows 158, 160, 162 for indicating a position of the color indicating portion 156 of the indicating plate 150, and a handle insertion hole 164 is formed at the center of the front plate 152 in order to insert a handle (not shown) for rotating the lead screw 104.
In the indicating means 107, when the indicating plate 150 connected to the cam 114 by the connection pin 124 moves up and down according to the rotation of the cam 114, the color indicating portion 156 provided on the indicating plate 150 is indicated with colors on the indicating windows 158, 160, 162 of the front plate in order to inform a user about a present position of the breaker body 200.
In the interlock apparatus of the draw out type air circuit breaker in accordance with the prior art, in order to connect the cradle 100 to the breaker body 200, the breaker body 200 is placed on a guide frame 14 of the cradle 100 and is pushed in, accordingly the breaker body 200 is moved into the cradle 100. When the lead screw 104 contacts to the screw pipe 106 according to the translocation of the breaker body 200 and a user rotates the lead screw 104 by using the handle, the lead screw proceeds into the screw pipe 106 while rotating.
Then, the two connection terminals 210, 212 projected from the breaker body 200 are inserted into the two connectors 206, 208 installed to the cradle 100, accordingly the power source terminal 202 and the load terminal 204 are connected each other.
When the lead screw 104 proceeds, the lead bar 112 contacts to the one wall surface of the cradle 100, herein the lead bar 112 moves in a direction opposite to the lead screw 104. As described above, when the lead bar 112 retreats, it rotates the cam 114 while moving along the slot 118 of the cam 114, by the rotation of the cam 114 the indicate plate 150 moves to the upper portion. Herein, a color indicating portion 156 provided on the indicating plate 150 is indicating one of the three indicating windows 158, 160, 162 of the front plate 152 in order to indicate a present position of the breaker body 200.
In more detail, when the two connection terminals 210, 212 projected from the breaker body 200 and the connectors 206, 208 installed to the cradle 100 are not connected each other, power is in the cut-off state, the color indicating portion 156 of the indicating plate 150 is indicated on the lowest indicating window 158 of the three indicating windows. Accordingly, the user recognizes a preset position as a disconnected position.
And, the lead screw 104 proceeds a certain degree, control power is applied, when the breaker body 200 reaches the testing position in which a user checks and tests each part of the breaker, the indicator plate 150 moves up a certain degree, the color indicating portion 156 is displayed on a middle indicating window 160 of the three indicating windows, accordingly the user recognizes the breaker body 200 is at the testing position. When the lead screw 104 proceeds completely, the connection terminals 210, 212 are inserted into the connectors 206, 208 installed to the cradle 100 and reaches the connected position in which main power is supplied, the color indicating portion 156 is indicated on the upper indicating window 162, accordingly the user recognizes the breaker body 200 is at the connected position.
However, in the position indicating t of the draw out type circuit breaker in accordance with the prior art, in order to indicate a position of a breaker body, because a color indicating portion of an indicate plate is indicated through a indicating window of a front plate, when a user can not distinguish colors, it is difficult to know a position of the indicating portion indicated on the indicating window with colors, in addition when impurities stick to the indicating, it is difficult is to recognize a color of the indicating portion.
In order to achieve the above-mentioned problems, it is an object of the present invention to provide a position indicating apparatus of a draw out type circuit breaker which is capable of distinguishing a position of a breaker body accurately even a user can not distinguish colors by improving a structure of the position indicating apparatus.
In order to achieve the above-mentioned object, in an air circuit breaker comprising a movable breaker body having a power source terminal and a load terminal and connecting or disconnecting a circuit between power and a load, a cradle electrically and mechanically connected/separated to/from the breaker body in accordance with movement of the breaker body and having connectors electrically and mechanically connected to the breaker body, a screw pipe for guiding the contact/separation to/from the breaker body and a power terminal and a load terminal respectively connected to the power source and the load, a base frame fixed to the breaker body, a lead screw supported by the base frame so as to be rotatable and movable to a position for being inserted into the screw pipe and a position for being separated from the screw pipe, a lead bar assembly having a lead bar supported by the base frame so as to perform a horizontal linear movement, extended so as to be parallel with the lead screw and linearly moving a distance corresponded to the translocation of the lead screw in a direction opposite to a forward direction of the lead screw when it is pushed in/drew out from the lead screw pipe and a spring for applying an elastic force to the lead bar in the insertion direction of the lead screw, a cam connected to the lead bar and for converting the linear movement of the lead bar into a rotation movement and a position indicating apparatus connected to the cam and for indicating a position of the breaker body according to the translocation of the lead screw, the position indicating apparatus comprises a first power converting means connected to the cam and for converting the rotation of the cam into a horizontal linear motion, a second power converting means connected to the first power converting means and for converting the linear motion of the first power converting means into the rotation, and an indicating means for indicating a position of the breaker body according to the rotation of the second power converting means.